package com.ssy.lingxi.common.utils;

import org.springframework.util.StringUtils;

import javax.crypto.*;
import javax.crypto.spec.SecretKeySpec;
import java.math.BigInteger;
import java.nio.charset.StandardCharsets;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.util.Base64;

/**
 * Aes 128bit加解密
 * @author 万宁
 * @version 2.0.0
 * @date 2020-11-21
 */
public class Aes128Util {
    /**
     * 密钥，固定16个字符
     */
    private static final String KEY = "GzSsyLingxi2.0.0";

    /**
     * 算法
     */
    private static final String ALGORITHMSTR = "AES/ECB/PKCS5Padding";

    public static void main(String[] args) throws Exception {
        //String content = "abcdABCD";
        String content = "lingxi888888";
        System.out.println("加密前：" + content);
        System.out.println("加密密钥和解密密钥：" + KEY);
        String encrypt = aesEncrypt(content, KEY);
        System.out.println("加密后：" + encrypt);
        String decrypt = aesDecrypt(encrypt, KEY);
        System.out.println("解密后：" + decrypt);
    }

    /**
     * aes加密
     * @param content 待加密的字符串
     * @return 加密后的Base64字符串
     * @throws Exception 异常
     */
    public static String aesEncrypt(String content) throws Exception {
        return aesEncrypt(content, KEY);
    }

    /**
     * aes解密
     * @param encryptBase64String	待解密的base64字符串
     * @return 解密后的字符串
     * @throws Exception 异常
     */
    public static String aesDecrypt(String encryptBase64String) throws Exception {
        return aesDecrypt(encryptBase64String, KEY);
    }

    /**
     * aes解密
     * @param encryptBase64String 待解密的base64字符串
     * @return 解密后的字符串，如解密失败则返回空字符串
     */
    public static String tryAesDecrypt(String encryptBase64String) {
        try {
            return aesDecrypt(encryptBase64String, KEY);
        } catch (Exception e) {
            return "";
        }
    }

    /**
     * 将byte[]转为各种进制的字符串
     * @param bytes byte[]
     * @param radix 可以转换进制的范围，从Character.MIN_RADIX到Character.MAX_RADIX，超出范围后变为10进制
     * @return 转换后的字符串
     */
    public static String binary(byte[] bytes, int radix){
        return new BigInteger(1, bytes).toString(radix);// 这里的1代表正数
    }

    /**
     * base 64 encode
     * @param bytes 待编码的byte[]
     * @return 编码后的base 64 code
     */
    public static String base64Encode(byte[] bytes){
        return Base64.getEncoder().encodeToString(bytes);
    }

    /**
     * base 64 decode
     * @param base64Code 待解码的base 64 code
     * @return 解码后的byte[]
     */
    public static byte[] base64Decode(String base64Code){
        return StringUtils.hasLength(base64Code) ? Base64.getDecoder().decode(base64Code) : null;
    }

    /**
     * AES加密
     * @param content 待加密的内容
     * @param encryptKey 加密密钥
     * @return 加密后的byte[]
     */
    public static byte[] aesEncryptToBytes(String content, String encryptKey) throws Exception {
        KeyGenerator kgen = KeyGenerator.getInstance("AES");
        kgen.init(128);
        Cipher cipher = Cipher.getInstance(ALGORITHMSTR);
        cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(encryptKey.getBytes(), "AES"));

        return cipher.doFinal(content.getBytes(StandardCharsets.UTF_8));
    }


    /**
     * AES加密为base 64 code
     * @param content 待加密的内容
     * @param encryptKey 加密密钥
     * @return 加密后的base 64 code
     */
    public static String aesEncrypt(String content, String encryptKey) throws Exception {
        return base64Encode(aesEncryptToBytes(content, encryptKey));
    }

    /**
     * AES解密
     * @param encryptBytes 待解密的byte[]
     * @param decryptKey 解密密钥
     * @return 解密后的String
     */
    public static String aesDecryptByBytes(byte[] encryptBytes, String decryptKey) throws NoSuchAlgorithmException, NoSuchPaddingException, BadPaddingException, IllegalBlockSizeException, InvalidKeyException {
        KeyGenerator kgen = KeyGenerator.getInstance("AES");
        kgen.init(128);
        Cipher cipher = Cipher.getInstance(ALGORITHMSTR);
        cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(decryptKey.getBytes(), "AES"));
        byte[] decryptBytes = cipher.doFinal(encryptBytes);

        return new String(decryptBytes);
    }


    /**
     * 将base 64 code AES解密
     * @param encryptStr 待解密的base 64 code
     * @param decryptKey 解密密钥
     * @return 解密后的string
     */
    public static String aesDecrypt(String encryptStr, String decryptKey) throws Exception {
        return StringUtils.hasLength(encryptStr) ? aesDecryptByBytes(base64Decode(encryptStr), decryptKey) : null;
    }
}
